It is the Question that has many "Problematic Parts" and each answer solves a different one. In the end, the User who asked the question could not pick which one to choose, so he picked a random one out of the N answers.

I do not know if anything similar has been discused in the past, and to be honest I did not find anything so I was wondering why we would have to narrow down accepted answers, to only one?

Since we use

The Green Mark for Accepting one answer, why shouldn't we as well have for example

The Orange Mark, which would be used to accept at least 2 and at most 3 answers in a post. The reputation gained by each user would be +10 for an accepted answer (instead of +15), but for the Question User would still be +3

The Blue Mark, which would be used to accept at least 4 and at most 6 and would give each Answer post +7, and would also give the Question Guy +3.

To try to avoid confusing new users, the option of selecting an Orange or a Blue mark would only be available after some reputation has been acquired (example 500).

4 Answers
4

Whilst the reputation barrier would avoid confusion for new users giving out the different coloured checks, it doesn't help newcomers who see them used from being confused. Since a good proportion of the hits from SO come from Google and from newcomers I think this would cause more confusion than it solved.

It'd also cause more effort in setting accepted answers, and there's the question of would people bother? Or if you're providing a reputation incentive so they do, why would they bother with just one accepted answer? I think if that were the case we'd see most questions with multiple accepted answers just for the sake of it.

Most of the time I do find there's a best answer available, and if not (if it's a case between two good answers) then I don't see the problem with picking one arbitrarily. It shows visitors that that's an answer that helped you solve the problem, if other answers are also very good then they're usually upvoted by the community and therefore highly visible anyway. Don't forget that the accepted answer can always be changed should an edit improve one of the answers.

And if we're talking opinions / questions with no one real answer, isn't that what the community wiki option is for?

I don't think this would be a good idea. If multiple answers share the same value the rule is that the fastest should be accepted. If they are different the upvotes lead to the best answer (by community acceptance).

People are lazy, even with a reputation of 500 they sometimes don't accept or upvote a good answer, or they accept it and don't upvote it. Don't make it more complicated.

Another point: In your scenario, why should I not just copy/paste with a little bit of an edit a very good answer and post it again.

And also: Don't expect the OP to come back to the question, after the problem is solved, just to check if there might be a better answer the OP could accept too.

Not because of multi-part questions, but for the situation where two answers propose equally valid solutions that happen to be different (the case with a few of my questions). Sometimes it is a matter of aesthetics or personal preference which solution is the best for a given situation.

Nor do I think it would need the extra complexity of requiring the questioner to specify how many answers they want to 'accept' in advance. Just let the questioner accept as many answers as they feel is appropriate. If you want to colour code the ticks, then just colour them according to the number of answers currently accepted.

I don't particularly care how the rep is handled from this either for questioner or answerer, maybe just divide up rep amongst all accepted answerers.